Created on:2021-11-24 10:06

Working principle of internal gear pump

Working principle of internal gear pump

At present, there are two kinds of tooth profile curves of internal meshing gear pump commonly used: involute gear pump and (also known as rotor pump) (see figure s). Their working principle and main characteristics are basically the same as those of internal meshing gear pump. The pinion is a driving gear. When rotating in the direction shown in the figure, the gear will withdraw from the meshing volume and increase oil absorption, and enter the meshing volume and decrease oil pressure. In the involute internal meshing gear pump cavity, a crescent diaphragm shall be installed between the pinion and the internal gear to separate the oil suction cavity and the oil pressure cavity [see Fig. s (a)]. The pinion and the internal gear of the cycloid tooth internal meshing gear pump differ by one tooth, so there is no need to set a diaphragm [see Fig. s (b)]. The internal gear pump has the advantages of compact structure, small size, light weight, stable operation, small flow pulsation and low noise. It has high volumetric efficiency when working at high speed. Due to the same steering of gears, the relative sliding speed between gears is small, the wear is small and the service life is long; However, the tooth shape is complex, the processing is difficult, and the price is higher than that of external meshing gear pump.

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At present, there are many kinds of cycloidal pumps in China. Figure t shows the structural diagram of BB-B cycloidal pump developed by Shanghai machine tool factory in 1975. The maximum working pressure is ≤ 2.5MPa. BB-B internal meshing cycloid gear pump is a positive displacement internal gear pump. Its internal gear (i.e. outer rotor) is a circular arc tooth shape, and the external gear (i.e. inner rotor) is a new type of gear pump with short amplitude external cycloid. Because the pump has the characteristics of simple structure, low noise, stable oil delivery and good self-priming performance, it is widely used in low-pressure hydraulic system. It is widely used in machine tools, gearboxes, compressors, transmission machinery, hoisting and loading machinery and other hydraulic systems with mechanical pressure lower than 2.5MPa. It can be used as power pump, lubrication pump and cooling pump to transport all kinds of oils.

Figure u shows NB series internal meshing gear pump. The structure of NB series internal meshing gear pump is straight tooth conjugate internal meshing single-stage gear pump.

Figure V shows the IP type involute internal gear pump.

Figure w shows GPA internal gear pump.

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